Linchpin



y 21, 1968 l. E. JACKSON ETAL 3,383,972

LINCHPIN Filed April 1, 1966 S m M 11mm; 5. Jae N f/EEEEET By M 2:. W

United States Patent 3,383,72 LINCHPIN Isaac E. Jackson, 1 Royle Ave., Glossop, Derbyshire, England, and Herbert H. Jackson, Woodseat Chase, Woodseats Lane, Charlesworth, Cheshire, England Filed Apr. 1, 1966, Ser. No. 539,453 3 Claims. (Cl. 85-5) ABSTRACT OF THE DISCLOSURE A linchpin used to secure machine parts in position which includes a shank, a head and a resilient clip which has a looped outer end from which a pair of parallel legs including inwardly turned free ends depend. The head includes a pair of offset, laterally disposed holes which receive the free ends of the clip and laterally extending cam means is located on the head for cooperation with the parallel legs of the clip to retain the clip against unintentional displacement.

This invention relates to linchpins or drop pins having a springy locking clip.

Considerable trouble and expense is experienced by users of linch or drop pins owing to the springy locking clip becoming loose resulting in the loss of the pins and damage to or loss of the machine part or component secured in position by the linch or drop pin.

Various methods have been used to overcome this disadvantage among which are the moving of the position of the pins; varying the size of the spring receiving holes drilled through the pin head; varying the angle of the holes in respect of each other and varying the shape and qualities of the spring. However, none of these methods have provided a satisfactory solution to the above-mentioned disadvantage.

An object of the present invention is to provide a linchpin or drop pin with an additional locking device for the springy locking clip so as to overcome the above-mentioned drawback.

According to the present invention there is provided a linchpin having a springy locking clip the ends of which are secured in offset, laterally disposed holes in the pin head, the head having at least one laterally disposed cam face which is engageable by the spring clip when being moved from its released position to its locked position, and which cam face co-acts with and securely holds the springy clip in its locked position.

Preferably, the linchpin head is formed with a second cam or projection on the opposite side of the head to the cam face, which second cam or projection is also engageable by the springy clip in its locked position to hold it under tension.

Conveniently, the second cam face has a recess into which the spring is located to hold the spring under tension in its locked position.

In order that the cam face and the second cam or projecting part may be kept as small as possible the parts of the spring clip adjacent its ends and to the head of the pin are preferably formed parallel to each other and lie closely together.

Alternatively, instead of providing a second cam or projection, the spring receiving hole on the opposite side of the head to the cam face is of a restricted depth which holds the spring under tension in its locked position.

In a preferred construction of the linchpin the head is formed with a hole into one end of which is inserted a domed headed rivet or pin such that the head of the rivet or pin head forms the cam face while the rivet or pin shank restricts the depth of the hole, for receiving one end of the spring locking clip to hold it under tension.

To enable the invention .to be clearly understood a number of preferred embodiments thereof will now be described by way of example with reference to the accompanying drawings, in which:

FIGURE .1 is a perspective view of a first embodiment of a linchpin with its springy locking clip in a released position.

FIGURE 2 is an end view of the linchpin illustrated in FIGURE 1 with the springy locking clip shown in secti-on for the sake of clarity.

FIGURE 3 is an end view similar to FIGURE 2 of a second embodiment of a linchpin partly in section.

FIGURE 4 is an end view of a third embodiment of a linchpin.

FIGURE 5 is an end view partly in section of a fourth embodiment of a linchpin, and

FIGURES 6 and 7 show in elevation and plan view two forms of a rivet .or pin for use with the linchpin shown in FIGURE 5.

Referring to the said drawings, the first embodiment of the linchpin illustrated in FIGURES 1 and 2 comprises the conventional shank 1 with a head 2 having a pair of laterally disposed holes 3 offset from each other and passing completely through the head. These holes receive the free inwardly turned ends of a springy loop-like locking clip 4 which includes a pair of parallel leg portions adjacent said free ends. To look the springy clip 4, it is moved from the position illustrated in FIGURE 1, i.e., its released position, to a locked position where the centre of its loop lies against the shank 1. To hold the springy clip 4 in this locked position the base of the pin head 2 is formed with a laterally extending flange on each side, the flange on one side being shaped as a cam face 5 while the flange on the other side is formed with a second cam or projection flange 6. When the springy clip 4 is moved to its locked position one of said leg portions engages behind a nose of the cam face 5 which holds it locked against the pin shank 1 while the opposite leg portion engages behind the other cam or projection 6 holds the clip under tension.

In the second embodiment of the linchpin illustrated in FIGURE 3 the second cam or projection flange 6 is omitted and one of the holes 3 is made blind and of restricted depth so that the spring end received in this hole is held under tension.

FIGURE 4 illustrates a third embodiment of the linchpin similar to FIGURE 2 except that the second cam or projection 6 is formed with a recess 7 for locating and tensioning the springy clip 4.

A fourth embodiment of the linchpin is illustrated in FIGURE 5 in which a rivet or pin 8 is located in an unoccupied end of one of the drilled holes '3 and replaces both the cam face 5 and the cam or projection 6. This rivet or pin 8 has a shank 9 and a dome shaped head 10 as shown in detail in FIGURE 6. The shank 9 has a serrated or knurled portion 11 so that the rive-t or pin 8 can be held with a forced fit in the hole 3. When positioned in the hole 3, the rivet or pin 8 closes one end of the hole 3 restricting its length and thereby tensioning the spring as described with reference to the second embodiment. At the same time the domed head 10 constitutes the cam face 5. The head 10 of the rivet or pin 8 need not be a complete hemisphere but only a part thereof as illustrated in the embodiment shown in FIGURE 7.

The cam face and projecting flanges 5 and 6 are kept to minimum dimensions by shaping the spring locking clip 4 such that its free end portions are parallel to each other and lie closely together.

The flange on the base of the pin head 2 which is shaped to form one or both of the cam faces 5 and 6 may be produced by a method of cold forging the linchpin, according to a modification of the method described in our copending patent application No. 532,909.

The modified method comprises the steps of cold forging a length of wire stock in a cold heading machine to form a blank with a head, and a round die-pointed shank, the cavity or recess in the heading punch being thrown off-centre, such that a flash or flange is formed on the inner periphery of the head, placing the blank in a power press and producing a fiat on the shank and deforming it to a larger diameter, placing the blank in a power press to extend said flat in the same plane along the head, and subsequently shaping the said flash or flange to provide one or both of the cam faces 5 and 6, and trimming the head to the required size.

The pins according to this method can be manufactured from any material suitable for cold heading, such as steel, copper, brass, Monel metal or any material suitable for cold forging.

The method according to the invention has the advantage that the original size of the wire stock from which the pins are made has a smaller diameter than the shank of the finished pin economising in material and eliminating waste, and the components of the pin can be maintained at close dimensional tolerances.

We claim:

1. A linchpin comprising a pin portion and a head, said head having a pair of offset laterally disposed holes therein, a looped springy clip including two free end portions thereof engaged respectively one in each of said holes, said clip further including substantially parallel leg portions adjacent said free end portions, cam means on said head at the junction with said pin portion and projecting laterally thereof, at least one of said leg portions of said clip co-acting with said cam means when moved to a locked position, whereby said clip is held secured against unintentional displacement.

2. A linchpin according to claim 1, wherein said cam means comprises a first laterally directed cam portion over which one leg of the spring clip can be sprung when locked and be yieldingly held against movement in an unlocking direction, and a second laterally directed cam portion engaging the other leg of the clip to hold the clip under tension in said locked position.

3. A linchpin according to claim 1, wherein said cam means extends laterally from one side of said head, one of said holes being a through hole for receiving one free end of the springy clip, the other of said holes being a blind hole of limited depth for receiving the other free end of the springy clip, said cam comprising the domed head of a rivet which is engaged in the second mentioned hole to form a blind bore which restricts the depth of said hole to thereby limit penetration of the associated free end of the springy clip to keep the latter under tension when the clip is moved to a locked position.

References Cited FOREIGN PATENTS 218,550 4/1909 Germany.

EDWARD C. ALDEN, Primary Examiner.

RAMON S. BRITTS, Assistant Examiner. 

